Method of degreasing wool and recovery of wool grease



2,833,798 Patented May 6, 1958 NIETHOD F DEGREASING WOOL AND RECOVERY OFW001. GREASE Daniel P. Norman, llpswich, Mass, assignor to PacificMills, Lawrence, Mass., a corporation of Massachusetts No Drawing.Application November 2, 1955 Serial No. 544,612

7 Claims. (Cl. 26ll--412.8)-

(CH Cl thereby removing both the wool grease and the suint in a singleextraction operation and providing a well scoured wool, and withoutproducing waste of objectionably high B. O. D.

An object of the present invention is to improve upon the process of myprior application. A further object is to provide a solventWool-scouring process wherein both grease and suint are removed in asingle operation and which is more eflicient than prior processes. Afurther object is to provide a methylene chloride wool-scouring processwhich is more rapid and hence less expensive than priorprocesses.

In accordance with the present invention I have now found that theaddition to the scouring bath, either just before or at the same time asthe methylene chloride is applied to the wool, of a small amount ofwater, or, less preferably, of a polar organic liquid which is solublein methylene chloride, unexpectly greatly increases the efliciency ofthe scouring process, particularly with respect to'removal of the suintcomponent of the raw wool, without in any way damaging the wool orincreasing the yield of undesirable wastes and, therefore, provides animproved process which is less expensive and more rapid than priorsolvent degreasing processes.

The following examples are given by way of illustration and disclosureof my invention without the intention.

of limiting it thereto.

Example I Four pounds of a commercial blend of fine Australian woolcontaining 7.94% suint, 3.35% potassium and 16.25% grease was picked andthen treated in a stainless steel drum with a volume of extractingliquid just sufiicient to completely immerse it. This extraction liquidconsisted of methylene chloride saturated with water, i. e., methylenechloride containing about 0.198% of its weight of water. The wool wasslowly agitated in the liquid at room temperature, drained on anopen'stainless steel screen and a small portion was removed, dried andanalyzed. The remaining wool was then again treated in the same mannerwith a fresh batch of scouring liquid. This procedure was repeated togive a total of four scours. Inasmuch as the suint of wool is composedprimarily of organic potassium salts or soaps, the potassiumconcentration is an excellent measure of the amount of suint present onthe wool. Potassium determinations on the wool at the end of each scourgave the following results:

Percent Potassium remaining on the Wool (Dry Basis) Percent SolidsExtracted After Scour Number 99. cameo quoaoc:

Percent Potassium remaining (Dry Basis) After Scour Number showing thatthe presence of the water in the methylene chloride brings about a verysubstantial increase in the rate of removal of the suint salts, 3extractions being more effective in removing suint than 4 extractionswith dry methylene chloride. Since raw grease wool usually contains from10 to 18% moisture, it is quite unexpected to find that the addition ofaslittle as 0.198% of moisture to the methylene chloride would produce avery substantial increase in the rate of removal of the suint salts.

The same or even better results can be obtained by adding moisture tothe wool, thereby increasing the amount of water over the 0.198% maximumpossiblewhen water alone is mixed with the methylene chloride. Thisprocedure is illustrated in the following:

Example II Percent Potassium remaining on the Wool (Dry Basis) AfterScour Number Comparison of these figures with those of Example I.

shows that two extractions on 22% moisture-containing wool are moreefiicient than 4 extractionswith dry methy-' lene chloride on 12%moisture-containing woo1, an:-ad-- solubilizing compound or hydrotrope,i. e., a material which will increase the solubility of waterv inmethylenechloride.

Many such materials are known and I do notwish my invention tobe-confined to the use of any particular. one or ones. The followingexample illustrates my process employing sodium benzene sulfonateassuchi atmaterial.

Example 111 A batch of fine Australian wool as in Example I was scouredwith a solution of methylene chloride containing 0.25% of its weight ofsodium benzene sulfonate and water on the weight of the wool. After asingle extraction it was found that the amount of potassium left on thewool was only 1.0%, thus indicating that the increased water content ofthe scouring medium made possible by the solubilizing effect of thesodium benzene sulfonate was as effective in removing suint as was thesame amount of water when added to the wool. It is much easier,moreover, to add a hydrotrope and water uniformly to the methylenechloride than to add water uniformly to the wool.

Sodium xylene sulfonate may be substituted for the sodium benzenesulfonate in Example III, in the same amount, with equally good resultsand I do not intend to exclude salts of other alkyl aryl sulfonates, orexclude other classes of surface active agents.

In the claims I employ the term mixture to include not only mixtures butalso true solutions.

In accordance with the invention, I also may use a mixture of methylenechloride and a polar organic liquid which is soluble in the methylenechloride. Desirably this liquid is one which forms an azeotropic mixturewith the methylene chloride as thusthe subsequent distillationtreatment, to be described, is facilitated. Representative liquids aremethyl alcohol, methyl iodide, carbon disulfide, propylene oxide andglycol, which form such azeotropes, and isopropyl alcohol, acetic acid,benzoic acid, and dicyandiamide which do not. Of these I prefer methylalcohol as its behaviour is most like that of water. As the azeotrope ofmethylene chloride and methyl alcohol contains 8% methyl alcohol, thescouring bath will contain sufiicient methyl alcohol to introduce riskof felting if an efficient degree of agitation is employed. I prefer,therefore, to dilute this azeotrope with methylene chloride to theextent necessary to prevent undesired felting of the wool.

I believe that any polar organic liquid soluble in methylene chloride issuitable for removing the grease and suint from the Wool. In practice,however, there are severe limitations set on the liquids which can beused. These limitations are two-fold: first, the compound must meet thepractical criteria of not being too expensive, toxic, difficult torecover, or producing high 13. O. D. from small amounts that areeliminated with the miscella wash water. Secondly, it must be readilyremovable from the wool and, more importantly, from the grease. Mostwool grease today finds its ultimate use as a refined product (lanolin)for cosmetic use. Any compound which remains in the grease and could bea skin irritant would obviously be unsuitable for use where the greaseis to be so used, even though it would have the desired effect inimproving the initial wool scouring process.

I have found that the maximum rate of removal of suint salts in myprocess occurs when the amount of water or polar organic liquid presentis adjusted to be between about and on the weight of the wool, at thestart of the scouring operation, and enough such liquid is added duringsubsequent scours to maintain about 10% thereof on the dry wool basis.Maximum efficiency of scouring of grease wool by my process is achievedat a water content of about 22%. However, eflicient scouring can beeffected with water, or equivalent liquid, contents up to about If thecontent is increased above 35% the efliciency of the scour dropsrapidly, so that the gain in efiiciency of suint removal following fromsuch greater moisture content is completely offset by a less effectiveremoval of grease.

Also, too much water in the system may result in felting of the wool.Objectionable felting, or at least risk thereof, does not begin toappear, I have found, until the amount of water present is increased toabove about 30%, based on the weight of the wool. The absoluteefiiciency of the scouring operation depends in a great measure on thedegree of agitation of the wool in the liquid medium and the efiiciencywith which the medium is wrung out of the wool. Proper balance of thewater, or equivalent liquid, content against the severity of theagitation should be maintained to obtain the greatest over-allefliciency of the process. In practice a range of from 20% to 27% ofwater represents a very efiicient and practical level for scouring. Thisoptimum range can readily be obtained by spraying the wool coming fromthe picker or opener with a fine mist or by passing steam through it.Due to the fact that the scouring liquor is largely methylene chloride,my process permits active and efiicient agitation of the wool in thebath with little if any risk of felting of the wool, while approachingthe efficiency of the conventional aqueous scouring system, so far assuint removal is concerned.

The scouring liquor from the procedure of the foregoing examples isprepared for recovery of grease therefrom by washing it with an equalvolume of Water with violent agitation, preferably employing two washes.The miscellas formed by addition of water to these scouring liquors,surprisingly, do not form stable emulsions but readily break uponstanding or centrifugal treatment so that the aqueous layer containingthe suint and dirt is readily separated.

Analysis of a typical separated aqueous layer gave the followingresults:

First Washing Second Washing From Scour No.

Percent Percent B. O. D. Percent Percent B. 0. D.

K Grease K Grease Totals 1. 89 0. 40 0. 67 0. 530 0. 04 0.29

As shown by these data, the suint is effectively removed from thescouring liquor by water washing and the B. O. D. (biological oxygendemand) of the Wash water is very low per pound of raw wool.

The suint salts may be recovered from the wash water where this iseconomically practicable, thereby further reducing the B. O. D. of theeffluent. It is entirely possible in my process to discharge the wastewash water directly into a stream with little or no pollution problem, avery important advantage.

The water-washed grease-solvent miscella can be readily furtherprocessed by the procedures described in my said prior applicationSerial No. 274,820 to recover a high quality grease therefrom. Briefly,the miscella can be readily filtered and may be further purified bypassing it through an absorption column containing, for example,activated carbon, activated silica gel or activated clay for the removalfrom the grease of organic impurities. If desired the free fatty acidsof the grease may be neutralized and the resultant soaps washed out withwater.

Finally the solvent will be removed by distillation. Because of theremoval of color-forming impurities prior to distillation, which myprocess permits, the grease is not discolored in the distillationoperations, and a final grease product of exceptional quality mayreadily be produced.

My scouring process is not restricted to any particular type ofequipment. The process may be operated as a batch process or,preferably, as a continuous process. Desirably wholly enclosed equipmentis employed so that the methylene chloride may be recovered. Suitableequipment available commercially has been described in United StatesPatent No. 2,368,916, Drum et al., as well as in many older patents,such as No. 399,440, to Shuman.

In one preferred type of apparatus, the methylene chloride and Water issprayed onto the wool as it moves along a continuous conveyor, the Waterbeing sprayed either simultaneously with or immediately preceding themethylene chloride spray.

In one such operation employing counter-current extraction, the moistureon the wool was adjusted to 22% at the start, water-saturated methylenechloride was employed and the ratio of the methylene chloride to thewool was approximately 30 to 1 by weight. It was found that thepotassium content was reduced to 0.25% and the grease content to 0.2%,both by Weight on the wool. In contrast, dry methylene chloride aloneunder identical conditions required a ratio of methylene chloride towool of 280 to 1 to produce the same results. In the operation justdescribed, of Water, by weight of the wool was added just before thefirst scour, subsequent scourings then being performed withwater-saturated methylene chloride Without addition of further water.This is a very convenient operating compromise which gives a highdesuinting rate with a minimum of control difiiculties. The desuintingrate can be increased by adding moisture to the wool at intermediatestages to maintain at least 10% moisture on the wool throughout thewhole scouring operation.

I claim:

1. The process for the removal of suint and Wool grease from raw woolwhich comprises leaching the raw wool containing wool grease and suintwith a mixture of methylene chloride and a liquid selected from theclass consisting of water and polar organic liquids soluble in methylenechloride, to extract wool grease and suint therefrom, the amount of saidliquid being less than 35% by weight on the Wool.

2. The process for the removal of suint and wool grease fro-m raw woolwhich comprises leaching the raw wool containing wool grease and suintwith a mixture of methylene chloride and a liquid selected from theclass consisting of water and polar organic liquids soluble in methylenechloride, to extract wool grease and suint therefrom, separating theliquid extract from the wool fibers, washing the extract with water, andseparating the aqueous phase containing suint from the non-aqueous phasecontaining wool grease, the amount of said liquid being less than 35% byweight on the wool.

3. The process for the removal of suint and wool grease from raw woolwhich comprises leaching the raw wool containing wool grease and suintwith a liquid mixture including methylene chloride and water, the amountof 6 the water being less than 35% by weight on the wool, thereby toextract Wool grease and suint from the wool, separating the liquidextract from the wool fibers, washing the extract with water, andseparating the aqueous phase containing suint from the non-aqueous phasecontaining wool grease. l 4. The method of claim 3 wherein the amount ofwater in the mixture of methylene chloride and water is increased by thepresence therewith of a hydrotrope as defined herein. i 5. The processfor the removal of suint and wool grease from raw wool which comprisesadding water to the raw wool to bring its Water content within the rangeto 35% Water by weight on the wool, leaching the so modifiecl wool withmethylene chloride to extract wool grease and suint therefrom,separating the liquid extract from the wool fibers, washing the extractwith Water, and separating the aqueous phase containing suint from thenonaqueous phase containing wool grease.

6. The process for the removal of suint and wool grease from raw woolwhich comprises adding water to the raw wool containing woo-l grease andsuint to bring its water content to Within the range 20% to 35% water byweight on the wool, leaching the so modified wool with a mixture ofmethylene chloride and water to extract wool grease and suint therefrom,separating the liquid extract from the Wool fibers, Washing the extractwith water, and separating the aqueous phase containing suint from thenonaqueous phase containing wool grease.

7. The process for the removal of suint and wool grease from raw woolwhich comprises leaching the raw wool containing wool grease and suintwith an azeotrope of methylene chloride and methyl alcohol, the amountof the alcohol being less than 35% by weight on the wool, thereby toextract wool grease and suint from the wool, separating the liquidextract from the wool fibers, Washing the extract with water, andseparating the aqueous-alcohol phase containing suint from thenon-aqueous-alcohol phase containing wool grease.

Gillespie: Wool Wax, page 24 (1948), Hobart Publishing 00 Inc.,Washington 15, D. C.

1. THE PROCESS FOR THE REMOVAL OF SUINT AND WOOL GREASE FROM RAW WOOLWHICH COMPRISES LEACHING THE RAW WOOL CONTAINING WOOL GREASE AND SUINTWITH A MIXTURE OF METHYLENE CHLORIDE AND A LIQUID SELECTED FROM THECLASS CONSISTING OF WATER AND POLAR ORGANIC LIQUIDS SOLUBLE IN METHYLENECHLORIDE, TO EXTRACT WOOL GREASE AND SUINT THEREFROM, THE AMOUNT OF SAIDLIQUID BEING LESS THAN 35% BY WEIGHT ON THE WOOL.